This project is to characterize the gene and protein structure and evolution of neurotransmitter receptors belonging to two major multi gene families. The gene families are those containing adrenergic, muscarinic, opsin, seratonin receptors and the second family containing nicotinic cholinergic, GABA/benzodiazepine and glycine receptors. The specific aims are to clone and sequence the genes for receptors in these two multigene families; to obtain very high density receptor expression and to use the expressed proteins to determine the complete structure of these receptors by x-ray crystallography and computer enhanced molecular modeling; to determine the evolution of the neurotransmitter receptor gene families; to search for and characterize receptor gene polymorphisms. To date we have cloned and sequenced a significant number of receptor genes from multigene families. These include beta 2-adrenergic receptors from human brain and genomic library, rat cardiac and rat genomic library and from shark genomic library. Beta 1-adrenergic receptors from a human genomic library; M1-M4 muscarinic cholinergic receptors from human, rat, shark and Drosophila genomic library. The human alpha-2 adrenergic receptor from a human genomic library; human alpha and beta subunits of the GABA/benzodiazepine receptor from human genomic libraries; adrenergic receptors from Drosophila cDNA and genomic library; nicotinic receptor genes from neuronal cDNA library and from locust cDNA libraries, and a chick genomic clone of the GABA benzodiazepine receptor. These receptors have been cloned into expression vectors and mammalian cells transfected. The results are permanent cell lines expressing the unique neurotransmitter receptor protein. The expressed receptor lines are providing key new information concerning the mechanism of receptors activated by neurotransmitters and a basis of receptor structural determinants.